CSS3 Text changes the definition of text-decoration to be a shorthand and adds a few more text-decoration-* properties:
text-decoration-color
text-decoration-style
text-decoration-line
text-decoration-skip
http://www.w3.org/TR/css3-text/#decoration
Gecko already implements the first two.

Nice catch Ojan :) I haven't sent yet, will send one later today, thanks for the reminder! And yes, good reminder about the dev one, though there are no apparent changes for text-decoration shorthands for now.
(In reply to comment #2)
> Have you sent an email to webkit-dev about this? See http://www.webkit.org/coding/adding-features.html.
>
> Also, not sure if this part of the spec has changed, but it's best to use the dev version of the spec since the TR version is often out of date (in this case by 6 months): http://dev.w3.org/csswg/css3-text/#decoration